Understanding Archive Bit and Backup Types

The archive bit is a file attribute that is set whenever a file is modified. For backups that use archive bits, this bit is turned off after the backup completes, indicating to the system that the file has been backed up. If the file is changed again before the next backup, the bit will be turned on and Genie Backup Manager will back up the file.

Whenever a file is created or changed, the operating system activates the Archive Bit or modified bit . By default, unless you specifically select to use the archive bit, Genie Backup Manager uses the last modified date and time stamp to determine whether a file has been backed up.

Using the archive bit in determining changed files, however, can cause confusion if the user is not careful, if the data selection for more than one backup job overlap. To explain this, consider this scenario: Jack has two backup jobs that he has scheduled to run consecutively, named Documents and Work . The folder Monthly Reports was selected to be backed up by both backup jobs. Come backup time, the job Documents, will backup the folder the turn off the archive bit. When its time for the job Work to run, it will find that the folder has already been backed up and skips the folder.

When the archive bit method is used with full, increment or mirror backup, GBM will turn off the archive bit after each backup run. However, when used with differential backup, GBM will only reset the bit in the first full backup, but not in subsequent differential runs, this way, GBM will always keep backing up files that have changed since the first full backup.

To set GBM to reset the archive bit after backup:
  1. From the left menu in the backup wizard Select Settings.

  2. Click More Settings then select Advanced Settings.

  3. Select Reset the Archive Bit.


To use the archive bit in determining changed files:
  1. Click the Start menu in the Windows toolbar, then select Run.

  2. Type regedit.

  3. Browse the registry until you reach the following key:

  4. Double-click the value CompareMethod.

  5. Set the value to 0 (zero).